Here's a method I came up with to get past these roadblocks that has worked out very well for me. Play whatever pattern you are having trouble with....without your hi hat foot. What you need to do is first vocalize your hi hat part. Try saying the word "chick" every time you want your hi hat to close. Or if that is too hard, just grunt. If you can't vocalize the part, you won't be able to play the part. When you are able to vocalize the part, it's much easier to try to make your left foot follow your vocal.

If you have trouble vocalizing the part, what I do, is to downshift into just thinking the word "chick". When you can think it in time, then try saying it in time. When you can say it in time, then try playing it in time. I use this method to clear mental hurdles, because it is all mental.